α-Fe2O3-Based Core-Shell-Nanorod-Structured Positive and Negative Electrodes for a High-Performance α-Fe2O3/C//α-Fe2O3/MnOx Asymmetric Supercapacitor

A alpha-Fe2O3/MnOx core-shell nanorod (NR)-based positive electrode is designed combining the traits of alpha-Fe2O3 and MnOx with an ultrathin MnOx shell serving as active site for surface or near-surface based fast and reversible faradaic-reactions and alpha-Fe2O3 NR core facilitating electron transfer toward the current collector. The alpha-Fe2O3/MnOx core-shell NR electrode shows ameliorated electrochemical performance in terms of capacitance and rate capability within the potential window of 0-1 V in relation to both pristine alpha-Fe2O3 NR electrode and pristine MnOx thin film electrode. Similarly, alpha-Fe2O3/C core-shell NR negative electrode is also realized. The assembled alpha-Fe2O3/C//alpha-Fe2O3/MnOx core-shell NR asymmetric supercapacitor (ASC) exhibits a volumetric capacitance of similar to 1.28 F/cm(3) at a scan rate of 10 mV/s with nearly 78% capacitance retention at the scan rate of 400 mV/s within a potential window of 0-2 V in aqueous electrolyte medium. Interestingly, the ASC delivers a maximum energy-density of similar to 0.64 mWh/cm(3) and a maximum power-density of 155 mW/cm(3), which are higher than the values obtained for alpha-Fe2O3//alpha-Fe2O3/MnOx core-shell NR ASC. Thus the study clearly exhibits the potency of core-shell nano-architechtured electrode design in realizing high-performance, cost-effective and environment-friendly ASCs. (C) The Author(s) 2017. Published by ECS. All rights reserved.